Thread-controlling mechanism for sewing-machines



R. BECKER.

THREAD CONTROLLING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JAN. 20, 1917.

1,, 3&9, 1 1 '5. P tented Aug- 10, 1920.

- 3 SHEETS-SHEET I.

ATTORNEY INVENTOR R. BECKER.

THREAD CONTROLLING MECHANISM FOR SEWING MACHINES. APPLICATION FILED JAN. 20. 191i.

1,341.9,1 15. Patented Aug. 10,192u.

3 SHEETS-SHEET 2.

ATTORNEY R. BECKER,

THREAD CONTROLLING MECHANISM FOR SEWING MACHINES.

APPLICATION FILED JAN- 20; 191i. 1,349,1 15

UNITED STATES PATENT OFFICE.

RUDOLPH BECKER, OF ROSELLE PARK, NEW JERSEY, ASSIGNOR TO THE SINGER MANUFACTURING COMPANY, A CORPORATION (3F NEJV JERSEY.

THREAD-CONTROLLING MECHANISM FOR SEWING-MACHINES.

Application filed January 20, 1917.

To all whom it may com-co n:

Be it known that I, RUDOLPH Bnonnn, a citizen of the United States, residing at Roselle Park, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Thread- Controlling Mechanisms for Sewing-Machines, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention relates to thread-controlling mechanism for sewing machines, particularly machines of the chain-stitch type employing thin flexible needles, and has for an object to provide a thread-controller which will accurately take up all the slack thread between the needle-eye and the work during the first part of the down-stroke of the needle, to prevent buckling or doubling ofthe thread below the needle-point and to maintain the previous needle-loop snugly about the blade of the retracting looper, without tightening the thread sufficiently to cause bending or deflection of the descending needle, even though the latter be extremely thin and flexible Another object of the invention is to provide a thread-controlling mechanism which will avoid the application of sudden stresses to the needle-thread and which will cause the stitches to be set with uniformity in different thicknesses of work without recourse to a compensating connection with the presser-bar.

More specifically, an object of the invention is to provide thread-controlling mechanism which is peculiarly adapted to meet the requirements of chain-stitch machines which have means below the throat-plate for deflecting a needle-loop on the loouer to one side of the line of scam formation, so that the descending needle may pass, into the triangular space formed by the looperblade, the looper-thread leading to the last stitch, and the deflected needle-loop.

A further object of the invention is to provide a needle-thread controlling mechanism which will reduce the size of the nascent needle-loop or loops to be seized by the advancing looper and prevent the twisting of said loop or loops out of the looper-path, or the crossing or entangling of said loops with one another on the looper-blade.

The invention has for a further object to provide a needle-thread controlling mecha Specification of Letters Patent.

Patented A11 10, 1920.

Serial No. 143,441.

nism which is constructed, arranged and timed to meet the conditions present in chain-stitch machines of the type having a vibratory plural-armed lever for imparting endwise reciprocatory movements tohthe needle and looper.

Still further, the invention has for an object to provide a thread-controller which will act in conjunction with take-up means to slow up and render uniform the pull-off action of said take-up means, and to avoid the application of sudden stresses to the needle-thread during the stitch-forming cycle and particularly during the pull-off pe riod of such cycle.

The above and other objects, to be more fully referred to hereinafter, are attained by the present improvement which may be embodied in a twinneedle single-looper machine of the flat-bed type having a needlebar actuating lever which is pivoted to the bracket-arm and adapted to transmit motion to the needle-bar and looper through the usual link-connections. In the present instance, the looper of the machine is formed with a shoulder near its heel to effect the lateral displacement of the needle-loops dur ing the first part of its loop-shedding stroke. A loop-detainer is mounted beneath the throat-plate to hold the needle-loops to one side after they slip over said loop-deflecting shoulder and prevent their being drawn forwardly along the looper-blade.

The thread-controlling mechanism, in its preferred form, comprises a pair of take-up guides, mounted on the needle-bar and needle-lever respectively, and a thread-controller adapted to act upon the thread between said guides. The thread-controller is preferably in the form of a small bellcranklever which is fulcrumed on the needle-lever near the link-connection between the latter and the needle-bar. The free arm of the bellcrankdever is formed with a thread-eye and carries a check-spring which, in effect, forms a yielding extension of said arm. The other arm of the threadcontroller is connected by a link to an actuating arm projecting from and forming a rigid partof the link-connection between the needle-lever and needle-bar. The centers of pivotal connection are so chosen that the actuating connections for the threadcontroller constitute a toggle-device which serves to impart a rapid differential movement to the thread-controller relatively to the needle-lever while the needles are out of the work, followed by a substantial dwell eluding a slight reversal of motion relatively to the needle-lever while the needleeyes are below the throat-plate. At the end of the up-stroke of the needle, the threadengaging means of the thread-controller move into substantial alinement with the take-up guides.

In the accompanying drawings, Figure l is a front elevation of the machine with the shield-plate for the looper mechanism removed. Fig. 2 is a front view of the threadcontrolling mechanism at the period of the stitching cycle when the needle-loops on the looper are at the point'of slipping over the loop-detaining shoulder. Fig. 3 is a similar view with the needle-eyes entering thework and the needle-points entering the thread triangle formed by the needleand looperloops. Fig. 4 is a similar view with the needles at the end of their down-stroke. Fig. 5 is a plan view of the thread-controller. Fig. 6 is a vertical section on the line l1, Fig. 1. Fig. 7 is a perspective view of the thread-guide carried by the needle-bar. Fig. 8 is an enlarged view of the needles and looper at the period of the cycle illustrated in Fig. 2. Fig. 9 is a similar view of the needles and looper at the period of the cycle illustrated in Fig. 3. Fig. 10 is a bottom view of the throat-plate showing the looper at the end of its loopseizing stroke. Fig. 11 is a similar view showing the looper in the position it occupics in Figs. 2 and 8, and Fig. 12 a longitudinal cross-section through the throatplate showing the loop-detainer in side elevation. r

In the preferred embodiment of the invention as, illustrated, the machine comprises a frame formed with a base 1, standard 2 and overhanging bracket-arm 3 terminating in a head 4 provided with upper and lower bearing lugs 5, 6, in which is journaled the reciprocating needle-bar 7,

carrying the eye-pointed needles 8, 8, which in the present instance are very thin and flexible. Cast integral with the base 1 are the supporting posts 9 for the cloth-plate 10 which latter includes the raised por ion 11 apertured to receive the throat-plate 12 formed with the usual needle and feed-dog apertures 13 and 14, respectively, and carrying the loop-detainer 14 neath the cloth-plate 10 is the main-shaft 15 whose rearwardly projecting end is formed with a ball eccentric 16 and carries the combined handand pulley-wheel l7.

Embracing the ball-eccentric 16 is the strapped lower end of the pitinan 18 whose strapped upper end embraces the ball-ended pin 19 carried by the rearwardly projecting arm 20 of the three-armed needle-actuating Journaled be-,

lever 21 which is pivoted at 22 to the standard The downwardly extending arm 23 of said three-armed lever carries a ballended pin 24 which is embraced by one strapped end of the link 25 whose opposite strapped end embraces a similar pin 26, the shank 27 of which, Fig. 2, is clamped within a split socket 28 formed in the lug 29 which projects laterally from the looper-carrier 30. The looper-carrier 30 is pivotally mounted upon the rocking looper-support 31 rigidly secured to one end of a rock-shaft 32 whose opposite end carries a crank-arm 33 which is connected by a short pitman 34 to the eccentric 35 on the main-shaft 15. Rigidly secured within a suitable socket in the looper-carrier 30 is the shank 36 of the thread-carrying looper 37 which is formed with a thin blade 38, Fig. 10, terminating in a beak 39, and is provided at one side with a loop-deflecting projection or shoulder 40. As will be readily understood the eccentric 16imparts loop-seizing movements to the looper 37 while the eccentric 35 imparts the sidewise or so-called needleavoiding movements thereto.

The needle-bar actuating lever 21 is arched to conform to the shape of the bracket-arm 3 and terminates in a short horizontal extension 41 which carries the cross-pin 42, Fig. 6, whose oppositely pro jecting ends are embraced by the lower limbs of an H-shaped link .43 whose upper limbs embrace the similar pin 44 secured within an aperture 45, Fig. 7, in the laterally projecting boss 46 formed on the sleeve 4'? which surrounds and is secured to the needle-bar 7 by the screw 48.

A take-up thread-guide, in the form of a bracket 49 having thread-eyes 50, is secured to the sleeve 47 on the needle-bar by a screw 51. A. second take-up thread-guide 52 is secured to the needle-bar actuating lever 21 by a screw 53 and may be adjusted angularly about said screw. A stationary threadguiding pin 54 is secured to the standard 2 and engages the needle-threads leading from the usual tension devices 55.

upon the thread, particularly when the latter is being pulled from the supply. In the present instance the use of thin flexible needles adds to the difficulty of controlling the needle-threads since the slightest excess strain on said threads, during the first part of the clown-stroke of the needles, will cause the latter to be deflected sufiiciently to strike the throat-plate. On the other hand, the needle-threads must be closely under control at this time to maintain the looper-loops Eli) snugly about the shank of the looper, whereby the looper-loops may be deflected to one side of the needles by the shoulder on the looper-blade. Furthermore, since the loopdeflecting shoulder on the looper acts to deflect and slightly enlarge the needle-loops, a certain amount of thread must bedrawn downwardly through the work and must be supplied by the thread-controlling mechanism, otherwise the needle-threads will be unduly tightened and may cause deflection on the needles. In machines of the chain= stitch-type the take-up guides carried by the needle-bar and lever commonly act to pull thread from the supply as the needle-bar reaches practically the end of its up-stroke and, at high speed, this pull-ofl action amounts to a rapid succession of sudden jerks upon the thread, thereby unduly straining the latter.

To meet the above and other exacting requirements, as will be more fully explained, and to avoid sudden jerks upon the needlethread, particularly when it is being pulled from the supply, a threadcontroller has 1 been levised oi whlch the following is a description. This controller, in its preferred embodiment, comprises a check-spring 60 which forms a yieleing extension of one arm 61 of a bellcrank-lever which is pivoted to the needle-lever 21 at 62. The other arm 63 of the bellcrank-lever is pivotally connected by a screw-pin G l to one end or" a link 65 whose opposite end is pivotally connected by a screw-pin 66 to an angular extension 67 of one of the upper limbs of the i-i-shaped link 43 which connects the needlelever 21 to the needle-bar 7. The arm 61 of the bellcrank-lever is provided at its extremity with a thread-eye 67 and a downward extension 68, the lower end of which is extended inwardly to form a rest 69 serving to limit the downward movement of the check-spring 60 relatively to the arm 61. In the present instance, the centers of the pins 4-2, 66, 64: and 62 are so chosen that the link 4:3, including its extension 67, and the link.

65 form a toggle-device for actuating the arm 61 and causing the latter to move differentially with respect to the needle-lever while the needle-eyes are above the work and to move substantially as a fixed part of said needle-lever while the needle-eyes are below the work.

By referring to Figs. 3 and i it will be seen that there is a slight reversal of motion of the thread-controller as the central pivot the toggle-device crosses a line connecting the pivots 42 and 64. This reverse motion is practically negligible, however, in the present embodiment of the invention, a the checkspring- 60 is very largely depended upon to give up thread to the descending needles and to steal thread from the nascent needle-loops. However, by increasing this reverse motion and omitting the check-spring 60, the present slight takeup action of the thread-controller arm 6i, during the first part of the Lip-stroke of th needles, may obviously be increased sufiiciently to positively control the nascent needle-loops independently of the action or a check spring.

The machine is, of course, provided with suitable feeding mechanism including coacting work-engaging members such as the presser-i'oot 70 and the ieed-dog T1.

In the operation of the machine, starting with the needles at their highest point, l 1., the needle-threads are taut and extend substantially in a strai ht line from the take'up eye 52 through the eye 6? and run der the check-spring 60 to the tal e-up eyes 50. The previous needle-loops surround the looper-blade in rear of the shoulder 4:0, Fig. 10. As the needles begin their descent the thread-engaging arm of the thread-controller is caused to rock about its pivot 62 with a negatively accelerated motion. Said arm, therefore, acts rapidly at first to take up or absorb the thread given up by the descending thread-guides and the action being timed to slow up as the angle in the thread between the thread-guides 50 and 52 becomes less obtuse and the action oi the thread-engaging arm more effective. The needle-eyes are thus caused to slide down their respective threads which are wholly free from slack, yet are under no strain.

During the above described action of the thread-controller, the shoulder 40 deflects the needle-loops forwardly and to one side of the line of scam formation, thereby enlarging said loops and drawing a small amount of needle-thread down through the work. This action of the shoulder all), together with the combined actions of the thread-engaging elements 50, 52, and 6?, imposes a very slight stress upon the needlethread which lifts the weak spring 60 a slight distance above the rest 69, as shown in Fig. 2. As the needles descend further from the position shown in Fig. 2. the needle-loops slip over the shoulder 40, Fig. 11, and are immediately drawn against the loop-detainer 14c by the slight take-up ac tion or" the check-spring 60 in resuming its position in contact with the rest 69.

When the parts reach the position shown in Figs. 3 and 9, the needle-eyes are entering the work and the motion of tee thread-controller relatively to the needle-lever has practically ceased since the link has reached a position nearly in line with the cente' 42. The check-spring 60 is in contact with the rest 69. In passing from the position shown in Fig. 3 to that shown in F ig. 4 it will be seen that the center 66 crosses the line oining the centers 42 and 64, causing a slight reversal of motion of the V needles.

with said guides, shown in Fig. 1.

thread-controller arm 61 which gives upa slight amount of thread to the descending in the present instance, however, this reversal of motion is practically negligible and amounts merely to a dwell; the yielding action of the check-spring 60 being ahnost wholly depended upon to give up the thread required by the descending needles. The thread, therefore, is gradually strained as the needles near the end of their down-stroke to draw up and'set the needleloops shed by the looper. The check-spring 60 is of such strength that, when work of minimum thickness is being sewn, itwill yield just enough to supply the thread required by the descending needles without causing the needles to pull thread through the tensions.

As the needles rise from the position shown in Fig. 4, the check-spring 60 draws the needle-threads back through the needleeyes and reduces the size of the nascent needle-loops suftlciently to avoid crossing or entangling of said loops with one another and to avoid twisting of said loops out of the path of the advancing looper. After the needle-loops have been seized by the advancing looper and the needle-eyes have emerged above the work, the thread-controller begins its accelerated up-stroke, relatively to the needle-lever, to give up thread between the thread-guides 50 and 52 which have an excessive take-up action at this time.

The angle in the thread between the takeup guides 50 and 52 is now becoming more and more obtuse as the accelerated motion of the thread-controller guides carries them toward a position in substantial alinem lelrlit e give-up action of the thread-controller is thus timed. to lag slightly and uniformly behind the take-up action of the guides 50 and 52, whereby the latter begin to pull thread from the supply soon after the needle-eyes emerge above the work and continue to pull thread from the supply slowly and uniformly until they reach their highest position. Thus the pull-off stroke of the guides 50 and 52 is distributed over a considerable portion of the stitch-forming cycle and the needle-threads are gradually pulled through the tension devices instead of being suddenly jerked through the latter. The spring 60 yields slightly during the initial portion of the pull-off stroke and slowly approaches the rest 69 as the pull-off stroke progresses. This relieves the thread from sudden strain at the commencement of the pull-off stroke. The substantially alined position of the thread-engaging elements 50, 52, 60 and 67 near the end of the pull-ofi' stroke serves to reduce the friction on the thread and consequently imposed thereon. '1

lessens the strains If thicker work is presented to the needles, the additional thread required will be pulled off at the end of their clown-stroke; the thread being gradually strained as the check-spring 60 yields until the tension imposed upon the thread by the needles is sufficient to overcome that caused by the tensions 55..

By adjusting the take-up guide 52 toward the needle-bar, the angle in the thread between the take-up guides 50 and 52 is made less obtuse thereby rendering the threadcontroller more effective. The thread-controller will therefore give up more thread to the rising take-up guides 50 and and lessen the amount of thread measured from the supply. Consequently this adjustment will result in tighter stitching. By adjusting the guide 52 away from the needle-bar the stitches will be moreloosely formed.

While I have described the present improvement as embodied in a twin-needle machine it is to be understood that it operates in substantially the same manner to secure the same beneficial results in a single-needle machine. The invention is not to be considered as limited in its application to any particular type of sewing machine as the form and arrangement of the various parts are obviously susceptible of material modification to meet various conditions without departure from the spirit of the invention. Having thus set forth the nature of the invention, what I claim herein is 1. In a sewing machine, in combination, a needle, a looper, a needle-bar, a needle-bar actuating lever, a thread-engaging device carried by the needle-bar, a thread-controlling device mounted on the needle-bar actuating lever for differential movement relatively to the latter, and bodily movable mechanism for controlling said differential movement.

2. In a sewing machine, in combination, a needle, a looper, a needlebar, a needle-bar actuating lever, a thread-engaging device carried by the needle-bar, athread-controlling device mounted on the needle-bar actuating lever for differential movement relatively to the latter, and means operatively connected to said needle-bar for controlling said differential movement.

3. In a sewing machine, in combination, a reciprocating needle-bar carrying a needle, a looper, a tension-device, a needle-bar actuating lever, a plurality of thread-engaging devices carried by said needle-bar and its actuating lever, one of said thread-engaging devices moving upon and relative to said lever, said thread-engaging devices being adapted to move into substantial alinement near the end of the up-stroke of the needle-bar, thereby reducing the friction on the thread as it is being pulled through the tension-device.

4. In a sewing machine, in combination, a needle, a looper, a needle-bar, a needlebar actuating lever, a link-connection between the needle-bar and its actuating lever, thread-guide carried by the needlebar, a thread-controller mounted upon the needle-bar actuating lever for differential movement relatively to the latter, and means connected to said link for controlling said differential movement.

5. In a sewing machine, in combination, a needle, a looper, a needle-bar, a needlebar actuating lever, a link connection between the needle-bar and its actuating lever, a thread-guide carried by the needlebar, a thread-controller mounted upon the needle-bar actuating lever for differential movement relatively to the latter, and a toggle-device connecting said link with said thread-controller for giving to the latter a differential take-up movement during the I met part of the clown-stroke of the needle,

followed by a dwell occurring after the needle-eyes enter the work.

6. In a sewing machine, in combination, a needle, a reciprocating needle-bar, a thread-guide carried thereby, a needle-bar actuating lever, a thread-guide carried by said lever, a yielding thread-engaging device pivotally mounted on said lever for differential movement relatively to the latter and adapted to act upon the thread between said guides, and means for controlling the movement of said device about its pivot.

7. In a sewing machine, in combination, a needle, a needle-bar, a thread-guide car ried thereby, a needle-bar actuating lever, a thread-guide carried by said lever, a link connecting said needle-bar with said lever, a needle-thread controller adapted to act upon the thread between said guides, and

actuating means for said thread-controller including a toggle-device whose motion is determined by the movements of said link.

8. In a sewing machine, in combination, a reciprocating needle-bar carrying a needle, a looper, a lever for imparting reciprocating movements to said needle-bar and loop-seizing movements to said looper, needle-thread take-up elements carried by said needle-bar and lever respectively, and a toggle-actuated needle-thread controlling device mounted on said lever and adapted to act upon the thread between said elements.

9. In a sewing machine, in combination, a reciprocating needle-bar carrying a needle, a needle-bar actuating lever, a linkconnection between said needle-bar and le ver, a thread-engaging element movably mounted uponsaid lever, and an actuating connection between said link and threadengaging element for moving the latter relatively to said lever.

10. In a sewing machine, in combination, a needle, a looper, a needle-bar, a needle-bar actuating lever, a link connection between said needle-bar and its actuating lever, takeup means, a thread-controlling device cooperating therewith, and an actuating connection between said link and thread-com trolling device for determining its operative movements.

11. A thread controlling mechanism for sewing machines comprising, in combination, a needle-bar, a needle-bar actuating lever, a linkconnecting said needle-bar with said lever, a thread-engaging arm pivoted to said lever, and a link connection between said first-mentioned link and said threadengaging arm. 7

12. In a sewing machine, in combination, a needle, a looper, a needle-actuating lever, a yielding thread-controller mounted on said needle-actuating lever for differential movement relatively to the latter, means for imparting said differential movement to said thread-controller during the first part of the down stroke of the needle to take up the slack thread below the needle-eye, said means being constructed to cause said thread-controller to dwell relatively to said needle-actuating lever while the needle-eye is traveling below the work.

13. In a sewing machine, in combination, a reciprocating needle, a looper, needle-actu ating mechanism, looper-actuating mechanism, take-up devices, a thread-controller including a thread-engaging element, and means acting during the last part of the upstroke of said needle to impart an accelerated motion to said thread-engaging element to carry the latter toward a position substantially in alinement with said takeup devices.

14. In a sewing machine, in combination, a needle, a looper, a needle-bar, a needle-bar actuating lever, relatively moving threadguides carried by said needle-bar and lever, respectively, and a thread controller mounted for movement upon and relatively to said lever and adapted to act upon the thread between said thread-guides In testimony whereof, I have signed my name to this specification.

RUDOLPH BECKER. 

